What happened
On 15 October 2022, a Grob G10-3 Twin Astir II glider, registration G-CKRH, was performing a solo winch launch at Seighford Airfield in Staffordshire. The launch initially proceeded normally, but as the aircraft reached approximately 200 ft, the pilot heard a loud bang. Believing the winch cable's weak link had failed, the pilot lowered the nose. During this maneuver, the pilot noted dust rising from the cockpit floor due to negative G-forces.
Shortly after this, the pilot experienced a sudden impairment that hindered his ability to control the aircraft's flight path. While the pilot remained conscious, he was unable to manage the glider's pitch or deploy the airbrakes. The aircraft eventually struck the ground in a level attitude, bouncing into the air before undergoing two additional heavy impacts. The force of the collisions caused the fin and tailplane to detach from the fuselage and damaged the nose and forward cockpit. The pilot sustained one serious injury, specifically compression fractures to two vertebrae.
The investigation
The AAIB examined both the aircraft and the winch equipment following the accident. The investigation confirmed that the flying controls were correctly connected and the seat harnesses and new energy-absorbing cushions remained intact. The winch cable assembly was found to be in good condition, with the correct strength weak link still intact, suggesting the cable had either been released by the pilot or had back-released from the belly hook.
Investigators also looked into the pilot's recent health. The pilot had recently recovered from a bout of flu-like symptoms, and paramedics at the scene noted a low blood oxygen level, for which the pilot received oxygen treatment in the hospital. However, the CAA Medical Department determined that the low level of negative G-forces experienced during the launch was not sufficient to cause incapacitation, and there was no evidence of vestibular issues related to his recent illness.
Findings
- The pilot became briefly impaired following the decision to abort the winch launch.
- This impairment resulted in an inability to control the glider's speed, pitch, or airbrake deployment.
- The specific cause of the pilot's sudden impairment could not be established.
- The loud noise heard by the pilot may have been caused by the cable's ring moving within the hook jaw during the climb.